1. Technical Field
This invention relates generally to apparatus employed in the mixing of chemical concentrate with a diluting liquid. More particularly, it relates to an eductor for drawing chemical concentrate from a container and into the diluting liquid wherein the reduced pressure in the eductor can be easily adjusted.
2. Background Art
The use of eductors for mixing chemical concentrates into a stream of liquid to provide a diluted solution is well known. For example, see U.S. Pat. No. 5,927,338 and U.S. Pat. No. 6,279,598 issued to S.C. Johnson Commercial Markets, Inc.
Eductors without an air gap are known. One is described in U.S. Pat. No. 6,240,983 as well as EP 1 353 012 A1 and US 2003/0034078 A1.
Certain advances in technologies and changes in regulatory communities have given rise to non-air gap means of backflow prevention. One of the new backflow prevention methods is to use an elastomer in a critical path in such a manner that if a backsiphonage occurs, the elastomer will seal the path closed, thus preventing backflow. The atmosphere of an enclosed water supply system lends itself well to Herschel-type venturi systems. Vacuum profiles are based on standard inlet lengths, diameters and cone angles, which are proportional to exit throat lengths, diameters and cone angles. To change a vacuum profile requires a redesign of the entire venturi.
The prior art does not provide a non-air gap eductor wherein the vacuum profile can be changed without redesigning the entire venturi.
The objects of certain embodiments of the invention therefore are:
Providing an improved eductor for a mixing and dispensing apparatus.
Providing an improved non-air gap eductor.
Providing an improved non-air gap eductor wherein the vacuum profile can be changed without redesigning the entire unit.
Providing an improved non-air gap eductor of the foregoing type which can be easily retrofitted.
Providing an improved non-air gap eductor of the foregoing type which can be manufactured at minimal cost.